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[RFC,04/22] x86: Add macro to get symbol address for PIE support

Message ID 20170718223333.110371-5-thgarnie@google.com
State New, archived
Headers show

Commit Message

Thomas Garnier July 18, 2017, 10:33 p.m. UTC
Add a new _ASM_GET_PTR macro to fetch a symbol address. It will be used
to replace "_ASM_MOV $<symbol>, %dst" code construct that are not compatible
with PIE.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/include/asm/asm.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)
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Patch

diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 7a9df3beb89b..bf2842cfb583 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -55,6 +55,19 @@ 
 # define CC_OUT(c) [_cc_ ## c] "=qm"
 #endif
 
+/* Macros to get a global variable address with PIE support on 64-bit */
+#ifdef CONFIG_X86_32
+#define __ASM_GET_PTR_PRE(_src) __ASM_FORM_COMMA(movl $##_src)
+#else
+#ifdef __ASSEMBLY__
+#define __ASM_GET_PTR_PRE(_src) __ASM_FORM_COMMA(leaq (_src)(%rip))
+#else
+#define __ASM_GET_PTR_PRE(_src) __ASM_FORM_COMMA(leaq (_src)(%%rip))
+#endif
+#endif
+#define _ASM_GET_PTR(_src, _dst) \
+		__ASM_GET_PTR_PRE(_src) __ASM_FORM(_dst)
+
 /* Exception table entry */
 #ifdef __ASSEMBLY__
 # define _ASM_EXTABLE_HANDLE(from, to, handler)			\